At 10:25 PM -0500 7/30/01, Mark Hammons wrote:
This is from fellow list member Steve Goss. He came over to my house one
day with this lens and the 50mm 1.4 Zuiko. We used my Geiger counter
to test these 2 lenses and found the FTL lens to be radioactive but the
50mm Zuiko to not be. The other lens he talks about is my Leica
Screw-mount 50mm Summicron from about 1953 that uses Thorium
Oxide in the glass. As he states, the dominant decay type for Thorium
is Beta radiation ( A neutron in the nucleus of the atom kicks off an
electron and becomes a proton).
Beta radiation should be effectively meaningless in terms of radioactivity
unless you have a habit of taking lots of macro portraits of yourself, or
spend hours a day using the lens in question as a loupe. Range in air is
typically a few inches, range in metal, paper or plastic one the order of
0.5mm. (We were allowed to play with beta sources in college, but discouraged
from doing the same with gamma.)
paul
--
Paul Wallich pw@xxxxxxxxx
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